Hereditary angioedema is a rare but serious problem with the immune system that is passed down through families. It causes swelling, particularly of the face and airways, and abdominal cramping.

See also: Angioedema

Hereditary angioedema (HAE) is caused by low levels or improper function of a protein called C1 inhibitor. This problem affects the blood vessels. People with hereditary angioedema can develop rapid swelling of the hands, feet, limbs, face, intestinal tract, or airway (larynx or trachea).

Unlike an allergic reaction, there is usually no itching or hives. Swelling of the gut can cause intestinal cramping. If swelling closes the airway, it can be deadly. Attacks of swelling can become more severe in late childhood and adolescence.

There is usually a family history of the condition. However, relatives may be unaware of previous cases, which may have just been reported as an unexpected, sudden, and premature death of a parent, aunt, uncle, or grandparent.

Many attacks occur without reason. However, anxiety, stress, sickness (including colds and the flu), and surgery have been shown to trigger certain attacks of hereditary angioedema. Dental procedures increase the risk of attacks in patients with HAE.

• Swelling in the arms, legs, lips, eyes, tongue, or throat
• Airway blockage (involves throat swelling and sudden hoarseness)
• Repeat episodes of abdominal cramping without obvious cause
• Intestinal swelling can be severe and include vomiting, dehydration, pain, and occasionally shock

• Decreased C1 inhibiting factor activity
• Decreased C4 and C2 levels